Nacelle

ABSTRACT

A nacelle is configured to be coupled to an underside of a wing and forms a clearance space between the nacelle and a leading edge slat of the wing. A portion of an outlet cowling moves longitudinally aft when a reverse thrust configuration is activated and the leading edge slat is deployed toward the nacelle. The outlet cowling also includes another portion located adjacent to the leading edge slat that does not move when the reverse thrust configuration is activated and thus maintains its clearance space from the leading edge slat.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, claims priority to and thebenefit of, U.S. Ser. No. 15/702,424 filed Sep. 9, 2017 and entitled“NACELLE.” The '424 application is a continuation of, claims priority toand the benefit of, U.S. Ser. No. 14/939,638 filed Nov. 12, 2015 andentitled “NACELLE” which issued as U.S. Pat. No. 9,784,216 on Oct. 10,2017. The '638 application is a continuation of, claims priority to andthe benefit of, U.S. Ser. No. 14/590,668 filed Jan. 6, 2015 and entitled“NACELLE” which issued as U.S. Pat. No. 9,228,532 on Jan. 5, 2016. The'668 application is continuation of, claims priority to and the benefitof, U.S. Ser. No. 14/246,352 filed Apr. 7, 2014 and entitled “NACELLE”which issued as U.S. Pat. No. 8,931,736 on Jan. 13, 2015. The '352application is a continuation of, claims priority to and the benefit of,U.S. Ser. No. 13/410,933 filed Mar. 2, 2012 and entitled “NACELLE,”which issued as U.S. Pat. No. 8,727,275 on May 20, 2014. The '933application claims priority to and the benefit of U.S. ProvisionalApplication No. 61/591,715, filed Jan. 27, 2012. All of the abovereferenced applications are hereby incorporated by reference in theirentirety.

FIELD OF INVENTION

This application relates generally to engine nacelles, and, moreparticularly, to engine nacelle thrust reversers.

DESCRIPTION OF THE RELATED ART

A nacelle is a casing or housing that holds an engine and/or otherequipment on an aircraft. Nacelles are commonly coupled to an undersideof a wing, for example, by a pylon. Nacelles often include thrustreversers designed to decelerate the aircraft, usually just aftertouchdown. In conjunction with this, wing slats, when in a deployedposition, provide for greater lift when the aircraft is flying slowly.Thrust reverser systems often include cowlings that move aft when thereverse thrust is selected. Additionally, the leading edge of the wing,located above the nacelle, often includes leading edge slats that can bedeployed in a direction generally forward and downward, toward thenacelle. In large diameter turbofan engines installed under a wingconstrained in its distance from the ground, designs must be carefullyengineered so that movement of the cowling and leading edge slats duringreverse thrust does not cause the cowling to collide or otherwiseinterfere with the deployed leading edge slat. The present inventionssatisfy this requirement.

SUMMARY

The devices, systems, and methods of the present invention have severalfeatures, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this invention as expressed bythe claims which follow, its more prominent features will now bediscussed briefly. After considering this discussion, and particularlyafter reading the section entitled “Detailed Description,” one willunderstand how the features of this invention provide several advantagesover existing thrust reversers.

One aspect is a nacelle outlet cowling of a jet engine thrust reverser.The outlet cowling has a circumference measured from an outboard topedge to an inboard top edge. The outlet cowling includes a slidingportion beginning at the inboard top edge and having a circumferencethat is less than the circumference of the outlet cowling. The slidingportion is configured to move longitudinally between a forward thrustposition adjacent to a nacelle inlet cowling and a reverse thrustposition aft of the forward thrust position. The outlet cowling furtherincludes at least one stationary portion extending between the outboardtop edge and an edge of the sliding portion. The at least one stationaryportion remains in a stationary position when the sliding portion movesbetween the forward thrust position and the reverse thrust position.

Another aspect is a nacelle configured to be coupled to an underside ofa wing via a pylon. The wing comprises a leading edge slat configured toextend toward the nacelle when in a deployed configuration. The nacelleincludes a cowling having an outer translating sleeve configured to moveaft in a longitudinal direction and an outer fixed structure having aclearance distance to the leading edge slat when the leading edge slatis in the deployed configuration that remains substantially constantwhen the outer translating sleeve moves aft in the longitudinaldirection.

Yet another aspect is a method of reversing thrust of an engine fittedwith a nacelle on an aircraft. The nacelle comprises a cowling thatincludes an outer translating sleeve and an outer fixed structurelocated adjacent to an inboard lateral side of the outer translatingsleeve. The method includes moving the outer translating sleevelongitudinally from a first position to a second position aft of thefirst position without moving the outer fixed structure.

Further aspects, features, and advantages of the present invention willbecome apparent from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will now be described in connection with embodiments of thepresent invention, in reference to the accompanying drawings. Theillustrated embodiments, however, are merely examples and are notintended to limit the invention. The various features illustrated in thedrawings may not be drawn to scale. Accordingly, the dimensions of thevarious features may be arbitrarily expanded or reduced for clarity. Inaddition, some of the drawings may be simplified for clarity. Thus, thedrawings may not depict all of the components of a given apparatus,device, system, method, or any other illustrated component or process.

FIG. 1 is a perspective view of an aircraft incorporating a nacelleaccording to one embodiment of the present invention.

FIG. 2 is a perspective view of an underside of a wing of the aircraftof FIG. 1.

FIG. 3 is a perspective view of the nacelle of FIG. 1 in a forwardthrust configuration.

FIG. 4 is a cross-sectional view through the nacelle of FIG. 3 takenalong line 4-4.

FIG. 5 is a perspective view of the nacelle of FIG. 1 in a reversethrust configuration.

FIG. 6 is a side view of the nacelle of FIG. 5.

FIG. 7 is a rear view of the nacelle and engine of FIG. 5 in the reversethrust configuration.

FIG. 8 is a side view of a nacelle according to another embodiment ofthe present invention in a forward thrust configuration.

FIG. 9A is a perspective view of the nacelle of FIG. 8.

FIG. 9B is a perspective view of a nacelle according to yet anotherembodiment of the present invention in a forward thrust configuration.

FIG. 10 is a perspective view of the nacelle of FIG. 8 in a reversethrust configuration.

FIG. 11 is a perspective cut-away view of a portion of the nacelle ofFIG. 8 in a forward thrust configuration.

FIG. 12 is a perspective cut-away view of a portion of the nacelle ofFIG. 8 in a reverse thrust configuration.

FIG. 13 is a perspective cut-away view of a portion of the nacelle ofFIG. 8 in a reverse thrust configuration.

FIG. 14 is a partial cross-sectional view of the nacelle of FIG. 13taken along line 14-14, with the nacelle shown in a forward thrustconfiguration.

DETAILED DESCRIPTION

The following detailed description is directed to certain specificembodiments of the invention. However, the invention can be embodied ina multitude of different ways as defined and covered by the claims. Inthis description, reference is made to the drawings wherein like partsare designated with like numerals throughout.

The skilled artisan will recognize the interchangeability of variousfeatures from different embodiments. Although these techniques andsystems have been disclosed in the context of certain embodiments andexamples, it will be understood by those skilled in the art that thesetechniques and systems may be extended beyond the specifically disclosedembodiments to other embodiments and/or uses and obvious modificationsand equivalents thereof. Additionally, it is contemplated that variousaspects and features of the invention described can be practicedseparately, combined together, or substituted for one another, and thata variety of combination and subcombinations of the features and aspectscan be made and still fall within the scope of the invention. Thus, itis intended that the scope of the systems disclosed herein should not belimited by the particular disclosed embodiments described above.

Embodiments of the invention disclosed herein relate to nacelles thatincorporate a sleeve having a translating portion that moves whenreverse thrust is engaged, and a fixed portion that remains stationaryand does not move when reverse thrust is engaged. Such sleeves do notcollide or otherwise interfere with leading edge slat located on aleading edge of the wing above the nacelle when the slat moves downwardtowards the nacelle during flight. Nacelles disclosed herein can belocated closer to the wing, which increases the clearance between thenacelle and the tarmac or runway. This shift allows the fitting ofengines that have a higher bypass ratio (larger maximum diameter) to awing while maintaining the necessary clearance between the bottom of thenacelle and the tarmac or runway. In some implementations, providing ahigher bypass ratio engine can reduce thrust specific fuel consumptionfor an aircraft and improve overall fuel efficiency. Hence, the nacellesdisclosed herein can provide several advantages over existing nacelles.

FIG. 1 is a perspective view of an aircraft 10 having a fuselage 12 anda pair of wings 14 extending laterally from the fuselage 12. A nacelle16 is coupled to an underside of each wing 14. Although not illustratedin FIG. 1, in some embodiments, each nacelle 16 is coupled to a wing bya pylon, or any other suitable structure capable of coupling a load to awing.

Each nacelle 16 houses an aircraft engine 15, for example, a high bypassratio engine, which receives air through a fan 20 disposed near an inlet19 of the nacelle 16, combusts the received air with fuel within acombustion chamber, and provides an exhaust jet through a rear-facingnozzle to propel the aircraft 10 in a forward direction. Additionally,high bypass ratio engines also receive a substantial amount of airthrough the inlet 19 of the nacelle 16 that is passed over or bypassesthe engine 15 to provide additional thrust. The bypass air is combinedwith the exhaust jet and improves fuel efficiency and reduces enginenoise. Because a high bypass ratio engine can require a substantialamount of clearance between an exterior surface of the engine 15 and theinterior surface of the nacelle 16, such engines can require a largernacelle that must be disposed near the underside 17 of the wing 14 inorder to provide for necessary clearance between the nacelle and alanding surface such as a runway.

FIG. 2 is a perspective view of the underside 17 of the wing 14. Thenacelle 16 is coupled to the wing 14 by a pylon 18. The wing 14 includesslats 22 on the leading edge 24 of the wing 14. Slats 22 are aerodynamicsurfaces which, when in a deployed configuration illustrated in FIG. 2,can allow the wing 14 to operate at a higher angle of attack. A higherangle of attack can allow the aircraft 10 to fly more slowly or take offand land in a shorter distance. The leading edge slats 22 can also bedeployed after landing to increase drag, thus helping to decelerate theaircraft 10 more quickly. Deploying leading edge slats 22 after landingcan thus reduce wear on the brakes and allow for shorter landingdistances. The leading edge slats 22 are not normally retracted duringnormal flight operations to minimize drag. The retracted position isillustrated in FIG. 1, for example.

To assist in the description of the nacelles described below withreference to the figures, the following coordinate terms are used,consistent with the coordinate axes illustrated. A “longitudinal axis”is generally parallel to an axis of the nacelle that extends between theinlet and outlet of the nacelle. A “lateral axis” is normal to thelongitudinal axis and is generally parallel to a wing associated withthe nacelle. A “transverse axis” extends normal to both the longitudinaland lateral axes. In addition, as used herein, “the longitudinaldirection” refers to a direction substantially parallel to thelongitudinal axis; “the lateral direction” refers to a directionsubstantially parallel to the lateral axis; and “the transversedirection” refers to a direction substantially parallel to thetransverse axis. The terms “upper,” “lower,” “top,” “bottom,”“underside,” “upperside” and the like, which may be used to describenacelles and related components in the discussion below, are used inreference to the illustrated orientation of embodiments. For example,the term “upperside” is used to describe the portion of a nacelle thatis disposed above an engine housed within the nacelle. The term“underside” is used to describe the portion of the nacelle that islocated below the plane formed by the longitudinal and the lateral axesof the nacelle. Additionally, the term “forward” may be used to describethe portion of a nacelle located near the inlet of the nacelle. A firstcomponent disposed forward of a second component is generally locatedfurther away from a plane formed by the transverse and lateral axes ofthe nacelle than the second component. The “forward direction” refers toa direction substantially parallel to the longitudinal axis andgenerally moving from the outlet to the inlet of the nacelle. The term“aft” may be used to describe the portion of a nacelle located near theoutlet of the nacelle. A first component disposed aft of a secondcomponent is generally located further away from the plane formed by thetransverse and lateral axes of the nacelle than the second component.The “aft direction” refers to a direction substantially parallel to thelongitudinal axis and generally moving from the inlet to the outlet ofthe nacelle. A first component disposed “inboard” of a second componentis generally closer to the fuselage of an aircraft than the secondcomponent. A first component disposed “outboard” of a second componentis generally further away from the fuselage than the second component.

FIG. 3 illustrates a perspective side view of the nacelle 16 and theengine 15 housed in the nacelle 16. FIG. 4 shows a cross-sectional viewof the nacelle 16 and the engine 15 taken along line 4-4 of FIG. 3. Theengine 15 includes the fan 20 that is disposed near the front of thenacelle 16 to draw air into the nacelle through the inlet 19. A portionof the air drawn in through the inlet 19 is expelled through an outlet26 of the nacelle 16 and another portion is combusted with fuel toprovide a forward thrust for the aircraft 10. Additionally, air can beexpelled through a thrust reverser arrangement, described in greaterdetail below with reference to FIGS. 5 and 6, to produce a reversethrust. The nacelle 16 can be coupled to the aircraft 10 by the pylon 18disposed on the upperside of the nacelle 16. For example, the nacelle 16can be coupled to the underside of the aircraft wing 14 such that theengine 15 provides forward and reverse thrust capabilities to theaircraft 10.

Still referring to FIGS. 3 and 4, the nacelle 16 includes an inlet lipor noselip 27 and an inlet cowling 28. The noselip 27 and the inletcowling 28 can together define the inlet 19. The nacelle 16 alsoincludes an outlet cowling 30 disposed aft of the inlet cowling 26. Theoutlet cowling 30 can define the outlet 26 of the nacelle 16. The inletcowling 28 and the outlet cowling 30 can come together at splits, orjunctures, of the nacelle 16. For example, the nacelle 16 can include atransverse split 32 disposed between the inlet cowling 28 and the outletcowling 30.

The engine 15 extends along a longitudinal axis 34 of the nacelle 16.The engine 15 includes an exhaust nozzle 35 that extends through theoutlet 26 of the nacelle 16. Different components and compartments ofthe engine, e.g., a combustion chamber, may be housed within one or moreengine cowlings 36 that define an outer surface of the engine 15.

As schematically illustrated in FIG. 4, the fan 20 acts to draw incomingair 37 into the nacelle 16 through the inlet 19. A portion of theincoming air 37 may be diverted into the engine 15 and used forcombustion while another portion 38 of the drawn-in air 37 may bypassthe engine 15 and pass over the engine cowling 36. Thus, bypass air 38may exit the outlet 26 along with a flow of engine exhaust 39 to providea forward thrust relative to the nacelle 16 (e.g., to provide a forcethat thrusts the nacelle 16 and its associated engine 15 and aircraft 10from left to right as illustrated in FIGS. 3 and 4).

The nacelle 16 can include a thrust reverser system to temporarilydivert the bypass air 38, so that the thrust produced by the bypass air38 is forward, rather than aft. This diversion of air acts against theforward travel of the aircraft 10, decelerating the aircraft. Exhaustair can be redirected using blocker doors and cascade vanes disposedinside the nacelle 16, using mechanisms well known in the art. Reversethrust is typically applied just after landing, to decelerate theaircraft 10.

FIGS. 5 and 6 are a perspective view and a side view, respectively, ofthe nacelle 16 of FIG. 3 in a reverse thrust configuration. FIG. 7 is arear view of the nacelle 16 in the reverse thrust configuration.Referring now to FIGS. 5 and 6, activating a reverse thrustconfiguration translates the outlet cowling 30 longitudinally aft fromthe inlet cowling 28 as compared with the position of the outlet cowling30 in the forward thrust configuration (for example, as compared withthe position of the outlet cowling 30 illustrated above in FIGS. 3 and4). In this embodiment, the outlet cowling 30 is foil led of one unitaryor homogenous portion that extends continuously around the nacelle 16from a first, outboard longitudinal split 46 a to a second, inboardlongitudinal split 46 b (see FIG. 7). In other embodiments, the outletcowling 30 is formed of two or more portions that, together, extendaround the nacelle 16 from first split 46 a to second split 46 b.Activating the reverse thrust configuration moves the entire outletcowling 30 in the longitudinal direction from a first position to asecond position aft of the first position. In some aspects, the outletcowling 30 translates about two feet aft. The longitudinal movement ofthe outlet cowling 30 may be guided by the longitudinal split 46 abetween the outlet cowling 30 and pylon 18. Such longitudinal movementof the outlet cowling 30 acts to expand the transverse split 32 disposedbetween the inlet cowling 28 and the outlet cowling 30 and exposes anunderlying cascade 40.

The cascade 40 can include a plurality of vanes disposedcircumferentially about the longitudinal axis of the nacelle 16. Thevanes can redirect a flow of air from within the nacelle 16 through alattice of the cascade 40 such that the flow of bypass air 38 exits thecascade 40 and produces a reverse thrust. Additionally, as shown in FIG.7, as the outlet cowling 30 moves aft, blocker doors 42 are activated toimpede (for example, to prevent, inhibit, or reduce) the flow of airthat bypasses the engine 15 from passing through the outlet 26 of thenacelle 16. That is to say, the blocker doors 42 are activated to impedethe flow of air through an air pathway defined between the inlet 19 andthe outlet 26 of the nacelle 16. Instead of passing through the outlet26, the majority of the bypass air flow 38 is diverted by the blockerdoors 42 to pass through the cascade 40. The cascade 40, including aplurality of vanes and a lattice, acts to shape this flow of air suchthat a reverse thrust air flow 44 exits the cascade 40 in a directiontoward the inlet cowling 28 as illustrated in FIGS. 5 and 6. Incontrast, when in the forward thrust configuration, the outlet 26 of thenacelle 16 is substantially unimpeded by blocker doors 42 such that theengine exhaust 39 and bypass air 38 may freely exit the nacelle 16through an air pathway or duct from the inlet 19 to the outlet 26 of thenacelle 16.

FIG. 8 illustrates a side view of a nacelle 116 in accordance with oneembodiment of the present invention. The nacelle 116 is coupled to awing 114 by a pylon 118. The wing 114 includes a leading edge slat 122configured to move between a stowed position and a deployed positionwhich is illustrated in FIG. 8. The nacelle 116 includes a noselip 127,an inlet cowling 128, an outlet cowling 130, and an exhaust nozzle 135.The nacelle 116 also includes a cascade 140 underneath (that is,disposed radially inward of) a portion of the outlet cowling 130. InFIG. 8, the nacelle 116 is in a forward thrust configuration, such thatthe outlet cowling 130 is in a first position, stowed adjacent to theinlet cowling 128. The outlet cowling 130 includes an outer translatingsleeve 150 and an outer fixed (i.e., non-translating) structure 152. Thenacelle 116 also includes an outboard longitudinal split 146 a betweenthe outer translating sleeve 150 and the outer fixed structure 152.

The leading edge slat 122 can come into close proximity with the outletcowling 130 when the leading edge slat 122 is deployed downward towardthe nacelle 116. As described above with reference to FIGS. 3-6, areverse thrust condition deploys the outlet cowling 130 in the aftdirection and engages blocker doors to temporarily divert air in theforward direction. In aspects where activating a reverse thrustconfiguration moves the entire outlet cowling in the aft direction froma stowed position (for example, as with outlet cowling 30 of nacelle 16illustrated in FIG. 5), the present invention insures that the outletcowling does not slide into and come into contact with the deployedleading edge slat 122. Such contact could prevent the outlet cowling 130from moving aft to a fully deployed position because of interferencewith the deployed leading edge slat 122. Such interference could causedamage to the outlet cowling 130, the leading edge slat 122, and otherstructures in the wing 114 and the nacelle 116.

In one aspect of the present invention, the outlet cowling 130 includesan outer translating sleeve 150 configured to move longitudinally in theaft direction when the reverse thrust configuration is activated. Theouter translating sleeve 150 can move longitudinally from a firstposition to a second position aft of the first position. The outletcowling 130 also includes an outer fixed structure 152 located betweenthe outer translating sleeve 150 and the pylon 118. As described ingreater detail with reference to FIGS. 9 and 10 below, the outer fixedstructure 152 is fixed in place and does not move longitudinally in theaft direction when the reverse thrust configuration is engaged. As aresult, the outer fixed structure 152 does not come into contact withthe deployed leading edge slat 122.

FIG. 9A is a perspective view of the nacelle 116 of FIG. 8, withoutschematic depictions of the pylon 118, the wing 119, or the leading edgeslat 122. The outlet cowling 130 has a circumferential length 157measured from an outboard top edge 158 to an inboard top edge 159. Asdescribed above, the outlet cowling 130 includes an outer translatingsleeve 150 and an outer fixed structure 152. The outer fixed structure152 is located along the circumferential length 157 of the outletcowling 130 between the outboard top edge 158 and the outer translatingsleeve 150. The outer translating sleeve 150 extends circumferentiallyfrom the outer fixed structure 152 to the inboard top edge 159. Theouter fixed structure 152 extends circumferentially the distance neededto prevent the outlet cowling 130 that surrounds it from striking thedeployed slat when the outlet cowling 130 is translated aft into adeployed position.

A geometric plane formed by the transverse and longitudinal axes of thenacelle 116 defines an outboard portion 155 and an inboard portion 156of the nacelle 116. In certain embodiments, the outer fixed structure152 is longitudinally aligned with the outboard portion 155 of thenacelle 116, between an outboard portion 130 a of the outlet cowling 130and the pylon 118. The nacelle 116 may, but need not, include an outerfixed structure in an inboard portion 156 of the nacelle 116.

The outer fixed structure 152 can be located outboard of a first hingeaccess panel 160 a such that the outer fixed structure 152 is furtheraway from the plane formed by the transverse and longitudinal axes thanthe first hinge access panel 160 a. Additionally, an inboard portion 130b of the outlet cowling 130 can be located inboard of a second hingeaccess panel 160 b such that the inboard portion 130 b is locatedfurther away from the plane formed by the transverse and longitudinalaxes than the second hinge access panel 160 b.

Embodiments of the present invention are not limited to an outer fixedstructure 152 that is located in the outboard portion 155 of the nacelle116. Embodiments can also include a plurality of outer fixed structuresdisposed circumferentially around the upperside of the nacelle 116 toavoid contact between the outlet cowling 130 and the leading edge slat122 when one or both are deployed in a reverse thrust configuration.

FIG. 9B is a perspective view of a nacelle 216 according to anotherembodiment in which the nacelle 216 includes an outlet cowling 230having a plurality of outer fixed structures. The outlet cowling 230includes two outer fixed structures, a first outer fixed structure 252 alocated in an outboard portion 255 of the nacelle 216, and a secondouter fixed structure 252 b located in an inboard portion 256 of thenacelle 216. The second outer fixed structure 252 b can be disposed, forexample, between an inboard portion 230 b of the outlet cowling 230 anda second hinge access panel 260 b. The second outer fixed structure 252b does not move longitudinally when the outlet cowling 230 is moved aftduring reverse thrust, and can be configured to avoid contact between aportion of a deployed leading edge slat 222 located above the secondouter fixed structure 252 b.

FIG. 10 is a perspective view of the nacelle 116 of FIGS. 8 and 9A in areverse thrust configuration. The outer translating sleeve 150 of theoutlet cowling 130 has moved longitudinally from the first position,stowed adjacent to the inlet cowling 128, to a second position aft ofthe first position. The outlet cowling 30 also includes an innertranslating sleeve 162 that also moves longitudinally aft withactivation of the reverse thrust configuration. In one aspect, the outertranslating sleeve 150 moves in conjunction with the inner translatingsleeve 162 such that both sleeves move aft when reverse thrust isengaged. For example, the outer translating sleeve 150 can bemechanically coupled or unitary with the inner translating sleeve 162such that the outer translating sleeve 150 moves in conjunction with theinner translating sleeve 162. The movement of the outer translatingsleeve 150 in the aft direction to the second position exposes thecascade 140, allowing redirected air to exit the cascade 140 andcontribute to reverse thrust for the aircraft.

The outer fixed structure 152, which is located closest to the deployedleading edge slat 122, does not move with activation of the reversethrust configuration. The clearance between the leading edge slat 122when deployed and the outer fixed structure 152 does not change. Becausethe outlet cowling 130 does not extend into the region of the outerfixed structure 152 and instead is located farther away from thedeployed leading edge slat 122 than the outer fixed structure 152, theoutlet cowling 130 does not collide with the deployed leading edge slat122 when it moves in the aft direction.

In the embodiment illustrated in FIG. 10, an inboard portion 140 b ofthe cascade 140 is exposed when the outer translating sleeve 150 ismoved aft in a reverse thrust configuration. Redirected air can exit thecascade 140 through the now-exposed inboard portion 140 b, whereas aircannot be redirected out of the cascade 140 through the outer fixedstructure 152.

FIG. 11 is a perspective cut-away view of a portion of the nacelle 116of FIG. 8 in a forward thrust configuration. The nacelle 116 is coupledto a wing 119 having a leading edge slat 122. The nacelle 116 includesthe outlet cowling 130 and an inlet cowling (not illustrated in FIG. 11)The leading edge slat 122 has moved from a first, stowed position to asecond, deployed position just above the nacelle 116. The nacelle 116 isin a forward thrust configuration, with the outlet cowling 130 in afirst position, stowed adjacent to the inlet cowling. The outlet cowling130 includes a first portion, an outer translating sleeve 150,configured to move longitudinally from the first position to a secondposition aft of the first position. In some aspects, the outertranslating sleeve 150 moves aft in a longitudinal directionsubstantially parallel to a longitudinal axis 134 of the nacelle 116.The outlet cowling 130 also includes a second portion, an outer fixedstructure 152, that is configured to remain stationary when the outertranslating sleeve 150 moves aft to the second position. The deployedleading edge slat 122 is located just above the outer fixed structure152, but because longitudinal movement of the outer fixed structure 152in the aft direction does not take place, as described above, the outerfixed structure 152 does not collide or otherwise interfere with thedeployed leading edge slat 122.

FIG. 12 is a perspective cut-away view of a portion of the nacelle 116of FIG. 8 in a reverse thrust configuration. The first portion of theoutlet cowling 130, the outer translating sleeve 150, has movedlongitudinally to a second position aft of the first position. Movementof the outer translating sleeve 150 aft reveals a cascade 140 underlying(that is, located radially inward of) the outer translating sleeve 150,allowing air redirected by activated blocker doors to exit the nacelle116 and provide reverse thrust. A clearance distance 154 remains betweenthe nacelle 116 and the deployed leading edge slat 122 even when thenacelle 116 is in the reverse thrust configuration. The second portionof the outlet cowling 130, the outer fixed structure 152, has not movedlongitudinally in the aft direction and remains stationary above thenow-exposed cascade 140. The cascade 140 preferably does not lieunderneath (that is, is not located radially inward of) the outer fixedstructure 152.

FIG. 13 is a perspective cut-away view of a portion of the nacelle 116of FIG. 8 in a reverse thrust configuration. As described above, thenacelle 116 includes an outer translating sleeve 150 and an outer fixedstructure 152. The nacelle 116 also includes a hinge access panel 160located adjacent to and inboard of the outer fixed structure 152. Thenacelle 116 is in a reverse thrust configuration, with the outertranslating sleeve 150 in a second, deployed position that islongitudinally aft of a first, stowed position. In one embodiment, theouter fixed structure 152 is located between the hinge access panel 160and a longitudinal split 146 a formed between the outer translatingsleeve 150 and the outer fixed structure 152. The hinge access panel 160can allow access to internal components of the nacelle 116.

FIG. 14 is a partial cross-sectional view of the nacelle 116 of FIG. 13taken along line 14-14. Although the nacelle 116 of FIG. 13 is shown ina reverse thrust configuration, FIG. 14 illustrates a blocker door 142parallel to the outer translating sleeve 150, in a forward thrustconfiguration. The nacelle 116 can include an inner translating sleeve162 located radially inward of the outer translating sleeve 150 and theouter fixed structure 152. In some embodiments, activating a reversethrust configuration moves the outer translating sleeve 150 and theinner translating sleeve 162 longitudinally from a first positionadjacent to an inlet cowling to a second position aft of the firstposition. The outer translating sleeve 150 and the inner translatingsleeve 162 may move simultaneously.

The nacelle 116 includes a plurality of blocker doors 142 radiallyinward of the outer fixed structure 152. Activating reverse thrust movesthe blocker doors 142 in the aft direction, from a first (forwardthrust) position parallel to the outer translating sleeve 150 to asecond (reverse thrust) position. In some embodiments, the blocker doorsin the second position are perpendicular to the outer translating sleeve150. The nacelle 116 includes a cascade 140 configured to permit air toexit the nacelle 116 when the outer translating sleeve 150 and blockerdoors 142 moves aft. The outer translating sleeve 150 is disposedradially outboard of the cascade 140, but the cascade 140 preferablydoes not extend circumferentially to a location underneath (that is tosay, is not located radially inward of) the outer fixed structure 152.Movement of the outer translating sleeve 150 exposes the cascade 140,allowing air redirected by the blocker door 142 in the second positionto exit the nacelle 116 through the cascade 140.

The outer translating sleeve 150 can include an outer transverse side164, an inner transverse side 165, and an inboard lateral side 166. Theouter fixed structure 152 can include an outboard lateral side 167 andan inboard lateral side 168. The outboard lateral side 167 of the outerfixed structure 152 is adjacent to the inboard lateral side 166 of theouter translating sleeve 150. The inboard lateral side 168 of the outerfixed structure 152 can be adjacent to an upper track beam 170. Theupper track beam 170 is stationary in some aspects, and is locatedbetween the inboard lateral side 168 of the outer fixed structure 152and the hinge access panel 160. In some aspects, the outer fixedstructure 152 is coupled or attached to the upper track beam 170.

The outer fixed structure 152 can include features which guide the outertranslating sleeve 150 as it moves longitudinally aft from the firstposition to the second position. These features can include, forexample, one or more tracks, couplers, tongues, grooves, or otherstructures which allow the translating sleeve 150 to move or sliderelative to the outer fixed structure 152. In certain embodiments, theouter fixed structure 152 includes a track along which a groove in thetranslating sleeve 150 slides relative to the outer fixed structure 152.In certain embodiments, the outer translating sleeve 150 and the outerfixed structure 152 include male/female features which together form amating engagement that allows the translating sleeve 150 to move orslide relative to the outer fixed structure 152. Exemplary male andfemale features include tongue and groove members. The tongue member maybe located on the outer fixed structure 152 or the translating sleeve150 with the groove member being located on the other one of the outerfixed structure 152 and the translating sleeve 150. Of course theinvention is not limited to the disclosed arrangements of features andfurther includes other mechanical structures known to a person havingordinary skill in the art that would allow the translating sleeve 150 tomove or slide relative to the outer fixed structure 152.

In one aspect, the outboard lateral side 167 of the outer fixedstructure 152 includes an outer track 172. The outer track 172 canextend the length of the outer fixed structure 152 in the longitudinaldirection. The outer track 172 includes a groove 174. The groove 174accepts a mating tongue 176 of the outer translating sleeve 150. In oneembodiment, the mating tongue 176 is disposed adjacent to the innertransverse side 165 and the inboard lateral side 166 of the outertranslating sleeve 150. The tongue 176 is not limited to this location,however, and can be disposed in other positions, for example on theinboard lateral side 166 of the outer translating sleeve 150. The tongue176 and the groove 174 form a mating engagement in which the tongue 176slides longitudinally aft within the groove 174 when the outertranslating sleeve 150 moves longitudinally aft. Other matingengagements between the outer translating sleeve 150 and the outer fixedstructure 152 are within the scope of the present invention.

Nacelles described herein can advantageously include a mating engagementbetween an outer translating sleeve and an outer fixed structure withoutaffecting operation of an inner translating sleeve. In one aspect, forexample, the inner translating sleeve 162 moves longitudinally in theaft direction when the outer translating sleeve 150 moves longitudinallyin the aft direction. A portion 186 of the inner translating sleeve 162is located radially inward of the outer fixed structure 152. That is tosay, the portion 186 is located closer to the longitudinal axis 134 ofthe nacelle 116 than the outer fixed structure 152. When the innertranslating sleeve 162 moves aft to the reverse thrust configurationaccording to one embodiment, the portion 186 moves aft underneath theouter fixed structure 152 while the outer fixed structure 152 remainsstationary. Movement of the portion 186 underneath the outer fixedstructure 152 can advantageously allow a sufficient amount of a fan ductin the nacelle 116 to be blocked off by the blocker door 142 to meetperformance requirements. Accordingly, embodiments of nacelles describedherein can incorporate an outlet cowling that does not contact adeployed leading edge slat when the nacelle is placed in a reversethrust configuration, without modifying the structure or operation of aninner translating sleeve of the outlet cowling.

While the above description has pointed out novel features of theinvention as applied to various embodiments, the skilled person willunderstand that various omissions, substitutions, and changes in theform and details of the device or process illustrated may be madewithout departing from the scope of the invention. Therefore, the scopeof the invention is defined by any presented claims rather than by theforegoing description. All variations coming within the meaning andrange of equivalency of presented claims are embraced within theirscope.

What is claimed is:
 1. An outlet cowling of a nacelle, the outletcowling comprising: a sliding portion comprising an outer translatingsleeve and an inner translating sleeve distinct from and mechanicallycoupled to the outer translating sleeve, the outer translating sleeveforming a first portion of a circumference of the outlet cowling, thesliding portion configured to move longitudinally between a forwardthrust position and a reverse thrust position; and at least onestationary portion adjacent to the sliding portion, the at least onestationary portion aft of a transverse split line separating the outletcowling from an inlet cowling, the at least one stationary portionforming a second portion of the circumference, the at least onestationary portion configured to remain in a stationary position inresponse to the sliding portion moving between the forward thrustposition and the reverse thrust position.
 2. The outlet cowling of claim1, wherein the inner translating sleeve is disposed radially inward ofthe outer translating sleeve and the at least one stationary portion,wherein the outer translating sleeve is configured to move aftlongitudinally in conjunction with the inner translating sleeve.
 3. Theoutlet cowling of claim 1, further comprising at least one track, the atleast one track forming at least a portion of a mating engagementbetween the sliding portion and the at least one stationary portion. 4.The outlet cowling of claim 3, wherein the at least one track isdisposed in the sliding portion.
 5. The outlet cowling of claim 4,wherein the at least one track extends for the longitudinal length ofthe sliding portion.
 6. The outlet cowling of claim 3, wherein the atleast one track is disposed in the at least one stationary portion. 7.The outlet cowling of claim 4, wherein the at least one track extendsfor the longitudinal length of the at least one stationary portion. 8.The outlet cowling of claim 1, further comprising a tongue and a groove,one of the groove and tongue being disposed in the at least onestationary portion and the other one of the groove and tongue beingdisposed in the sliding portion.
 9. A nacelle comprising: an inletcowling; and an outlet cowling separated from the inlet cowling by atransverse split line, the outlet cowling including: an outertranslating sleeve and an inner translating sleeve configured to moveaft in a longitudinal direction; and an outer fixed structure locatedaft of the transverse split line, a forward portion of the outer fixedstructure forming a portion of the transverse split line, the transversesplit line separating the inlet cowling from the outer fixed structure.10. The nacelle of claim 9, wherein the inner translating sleeve isconfigured to move with the outer translating sleeve aft in thelongitudinal direction.
 11. The nacelle of claim 9, further comprisingan upper track beam, wherein the outer fixed structure is coupled to theupper track beam.
 12. The nacelle of claim 9, further comprising acascade located radially inward of the outer translating sleeve, whereinthe cascade is not disposed underneath the outer fixed structure. 13.The nacelle of claim 9, further comprising a plurality of blocker doors,a portion of at least one blocker door being located radially inward ofthe outer fixed structure.
 14. The nacelle of claim 9, furthercomprising an access panel configured to be located outboard of a pylon,wherein the outer fixed structure is located between the access paneland the outer translating sleeve.
 15. The nacelle of claim 14, whereinthe outer fixed structure is located outboard of the pylon.
 16. Thenacelle of claim 14, wherein the outer fixed structure is locatedinboard of the pylon.
 17. The nacelle of claim 9, wherein the outerfixed structure is located outboard of a pylon coupling the nacelle toan underside of a wing, and further comprising a second outer fixedstructure located inboard of the pylon, a clearance distance between aleading edge slat in a deployed configuration and the second outer fixedstructure remaining substantially constant when the outer translatingsleeve moves aft in the longitudinal direction.
 18. A method ofreversing thrust of an engine fitted with a nacelle on an aircraft, thenacelle comprising an outlet cowling including an outer translatingsleeve, an inner translating sleeve, and an outer fixed structure, themethod comprising: moving the outer translating sleeve and innertranslating sleeve longitudinally from a first position to a secondposition aft of the first position without moving the outer fixedstructure, the outer fixed structure being located aft of a transversesplit line between the outlet cowling and an inlet cowling, thetransverse split line extending between the inlet cowling and a forwardportion of the outer fixed structure, the transverse split lineseparating the inlet cowling from the outer fixed structure.
 19. Themethod of claim 18, wherein moving the inner translating sleeve from afirst position to a second position aft of the first position, comprisesmoving at least a portion of the inner translating sleeve disposedradially inward of the outer translating sleeve.
 20. The method of claim19, further comprising moving a plurality of blocker doors from a firstposition relative to the inner translating sleeve to a second positionrelative to the inner translating sleeve, the second position beingdifferent than the first position.